Retouching device



Jan. 17, 1950 J. B. STRAUGHN RETOUCHING DEVICE Filed Nov. 26, 1946OSCILLATOR NVENTOR James 17. Jtrau glm 2 ATTORNEY 'atented Jan. 17, 1950UNITED STATES PATENT OFFICE RETOUCHING DEVICE James B. Straughn, SilverSpring, Md.

Application November 26, 1946, Serial No. 712,298

3 Claims.

This invention relates to vibrating devices and particularly suchdevices that are intended for the retouching of photographic negatives.In the retouching art it has long been recognized that the vibrating ofa black lead or pencil (or a vibrating stand for holding the negative).is desirable. In the retouching other problems also arise in that thelead cannot be heavily or indiscriminately applied, for a heavy touchcauses streaks and above a limited amount seems to glaze the negative sothat the graphite does not take hold; on the other hand, the density ofapplication must be such as to give the correct contrast or to conformto that of the negative. To accomplish these ends a Wide variety ofmechanically vibrating devices, including armatures operated bymake-and-break magnetic means, have been proposed in order to reduce thetime and labor involved. But they have not come into general or anyextensive use, because the vibrations secured through mechanical meanshave been transmitted to or have taken place in the manually helddevices; not only is the weight necessary in such constructions tiring,but the continuous jarring is apt to have a numbing effect and theconstant shaking of the hand makes it difficult to apply the leadaccurately to a small point or area. To overcome or lessen theseobjections, vibrating stands for negatives have been proposed, but theyin turn import other difficulties, such as the heavy constructionnecessary and the practical impossibility of turning the negative asdesired, which a retoucher must frequently do to obtain good results;moreover, the mechanical vibrations of stands is likely to beaccompanied by distressing sound effects.

It has now been discovered that for overcoming the foregoing objectionsattending the vibrations of reto-.ching tools stands, the vibrationsshould have a simple harmonic motion, i. e., they should have afrequency and amplitude that can be represented by a harmonic (sine orcosine) curve. Vibrations of this character are found to be free fromany jarring effects, and they afford a smoothness of operation thatpromotes both efficiency and speed; when other waves are superposed, orif the wave departs materially from the pure sine wave, there is acorresponding roughness in the result. Even though the frequenciesselected are in the audible range, the sounds produoed are not annoyingor distracting.

For accomplishing the object of harmonic mechanical motion, it hasbeen'found that an electronic oscillator generating harmonic drivingpower is surprisingly effective when properly utilized. It has beenfurther found practical to translate this power into mechanicalvibrations for operating a retouching device by various means,preferably vibrating-reed electromagnetic devices and particularlypiezo-crystal elements suitably constrained to give the harmonic mechanical motion when subjected to electrostatic fields; thevibrating-reed electromagnetic and the piezo-electric elements have incommon that of being a vibrator responding mechanically to and inconsonance with the wave character of the electrical energy changesimposed on an electric field. With these types of energy converters, thesimple harmonic motion is faithfully conveyed to the retouching lead,there are no relatively heavy mechanical elements to be vibrated, a verylight construction is possible, and the vibrations created have nojarring or tiring effect.

It has been further found, however, that for retouching efficiently andspeedily with satisfactory effects, these devices should be operatedwithin a selected range of frequencies. Actual demonstrations appear toindicate a limitation upon the frequency range to be used to one ofabout 200 to 800 cycles per second; below that range the results are aptto be streaked or lined, and above that range there is a tendency tolift a graphite layer previously applied. Within that range theamplitude is open to variation by the power input to reg ..late thedensity of the applied coating; but for smoothness there seems to be anoptimum relationship between the amplitude and frequency selected thatcan be determined by trialv Since the range covers audio frequencies,audible hums are created when the lead touches the negative; but as theyare simple tones, they are not disagreeable or annoying, and in factthey serve a useful purpose in giving warning concerning the heavinessof the touch.

The combination of a sine-wave oscillator with an energy converter isattended with additional advantages. For retouching one grade of blacklead is not generally sufiicient due to the variations in densities ofnegatives or of different portions of the same negative requiringretouching, and with only one converter this means a changing of theblack lead; again with different grades of black lead and also withdifferent operators, changes in frequency may be required or. desirablefor best results. An oscillator, however, can be made to readily providea range of frequencies, either continuous or in increments by merelychangingthe tuning, and moreover a plurality of converters can beoperated simultaneously by a single oscillator. Or by tuning the tuningcontrol to obtain the most suitable frequency for a particular grade ofblack lead or for an individual operator, a converter carrying thatparticular grade of black lead can then be switched or plugged in. It isfurther possible to connect to an oscillator a plurality of convertersfor different frequencies by means of gan switches, so that by turningthe frequency control a converter operating at the selected frequency issimultaneously connected into the circuit.

While the preferred embodiments of the invention thus constitute anelectronic oscillator.

combined with an energy converter, it is possible to generate the simpleharmonic waves by other means. For instance, a generator ofalternatingenergy in the desired frequency range, and operated from a 60cycle power line, can be used as a source of power for driving theelectromagnetic or crystal devices; or a tone wheel of the type used inan electronic organ (described in Sales Instructions Bulletin No. 4issued by Hammond Clock 00., Chicago, Ill., as a disc with high pointson its periphery that rotates'in front of a pole of a permanent magnetwitha coil about the pole in order to create alternating energy in thecoil) can be substituted for the purpose. Essential to the invention isthe generation of alternating energy of substantially pure simpleharmonic wave c aracter in the useful frequencies and means for trans oming the currents into harmonic mechanical motion.

For adequately disclos ng the invention but not limited thereto,embodiments are illustrated in the accom anying drawing in which Fig. 1shows in vertical section a retouching stand in assembly w th anelectronic oscillator and a crystal typ retouching head;

Fi 2 is an enl rged vertical cross-section of the he d shown in Fig. 1and also shows diagrammet ca ly a suit ble oscillator circuit.

Fig. 3 shows in cross-sect on a modified form of c ystal-operated. head;and

F 4 is a v ew similar to F 3 illustrating anelectroma n tic head. orconverter.

The retouchi g st nd is of the usual ty e compri ing a box with a paneltop I2 h ving a ground lass 3. fitted over an opening 14. The negative'5 re ts on t e ground glass and a lamp is furnishes the ilhmination.

The crys al type of head or converter. shown in cr0ss-secti n in F g 2.cons sts of a cas ng 21. in the ca ty 22 of which is mounted apieZo-crystal' 23 of known con truction. Such a crystal commonly conists of one or more fi'at Rochelle salt prisms with sheets of metal foilon the o t r fiat" surfaces; when alternating ener y is ap lied thecrystal bends or twists in correspondence to the frequency. One end ofthe crystal is clamped in the cas ng by bars 24 and leads 25, 26 areconnected to the metal foils on the crystal. The other end carries acoupling member 21 that at its free extremity 28 is bedded in a rubberbushing 30. As part of the coupling member is a chuck 3| with a setscrew 32 for securing the retouching black lead 33.

A simple oscillator circuit is selected for illustration, and thiscomprises resi tors R1 (4,000 ohms), R2 (e00 ohms), Rs (50,000 ohms),condenser C1 (.01 microfarad), and a tube oi." the 6F6 type in circuitwith the secondary of a feedback transformer T1; the energy is suppliedto the tube by a power pack generally indicated, by P. The secondarycircuit is shunted by a plurality of condensers C3, of. differentcapacities and, a step switch S1 connects in any one of the conform morenearly in shape to a pencil. In this the crystal, clamped in the casing41, carries the coupling member 42 bedded in the rubber bushing 45, andon, the member 42 is an extension 43 with set screw 44 for receiving theblack lead.

Evi'dently' with this construction the black lead traces tiny menisciwhen the crystal twists under the influence of the electric energy torotate the member 42 about its axis.

In Fig. 4 the crystal is substituted by an electromagnet comprisingwithin the casing the arms 52, 53 of soft iron secured at one end to ablock 54 of f'eralloy. A coil 55 surrounds the free ends of the arms,and between the opposing poles a reed armature 5'1 mounted at each endin rubber cushions 58 and 59; underthe influence of the electric energythrough the coil 55, the reed armature vibrates between the poles with amechanical wave motion corresponding to that of the imposed electricenergy. The armature carries a chuck 60 with set screw 61 for securingthe black lead to transmit to the latter the vibrations of the armature.

In operation the oscillator is set to the frequency selected byconnecting in the condense] C3 for that frequency. The intensity of theoutput is controlled through the potentiometer R4; for simplicity thepotentiometer is shown part of the oscillator, but it can be separatedand mounted in a box or plate on the retouching stand. When theoscillator is operating, a gentle hum can be heard in the retouchinghead, since the frequencies operable for retouching lie in the audiorange. The hum means that the black lead is vibrating at the frequencyof the oscillator wave, and the translation into mechanical vibration iscaused by the crystal in Figs. 2 and 3 and by the electromagnet andvibrating reed armature in Fig. 4. The vibrating black lead is touchedtc the negative, and the desired density or blotting out of defects isspeedily accomplished. If the amplitude or intensity is too much or toolittle the potentiometer is varied to give the correct energy output.

What is claimed is:

1. Retouching device comprising in combination with a source of electricenergy of substantially simple harmonic wave character, a head havingmeans connected by leads to the source for converting the electricenergy into mechanical vibrations of like wave character, said meansincluding a piezo-crystal element, and means for retouching carried bthe head and connected tc the crystal element for vibration thereby.

2. Retoucher comprising in combination 2 piezo-crystal element forconverting electrica energy of harmonicwave character into mechani calvibrations of like wave character, means i 01 retouching connected withthe element for vibration therewith, and leads extending from theelement for connection to a source of the electrical energy.

3. Retoucher comprising in combination 2 energy of harmonic wavecharacter into mechani- REFERENCES CITED cal vibrations of like wavecharacter, means for maintaining one end of the element in fixed pog figgi fg are of record in the sition, a. coupling member secured to theother p end of the element for vibration therewith, means 5 UNITEDSTATES PATENTS for retouching carried by the coupling member,

and leads extending from the element for congggg g Mar 3 9 nection to asource of the electrical energy. 1 352976 Kugle} Se 1920 JAMES B.STRAUGHN. p

2,012,797 Whitman Aug. 27, 1935

